The current invention relates generally to foot operated pedals, specifically to bicycle pedals and particularly to bicycle pedals operated in conjunction with shoe cleats.
Effective transmittal of torque between shoe and pedal is crucial to cycling efficiency. A compromise with safety is observed. Rigid attachment of shoe to pedal achieves optimal efficiency in enabling transmission of force evenly through full rotation, but totally abandons safety. A platform pedal presents no impediment to safety, but only allows application of force downwards. A toe clip and strap compromises; the tighter the strap, the more efficiency gained and safety sacrificed. Recent `clipless` style pedal and cleat systems adapted from certain ski bindings require rotation to effect release and involve a similar compromise.
An alternative approach employing longitudinally or axially tracked pedals and shoe cleats shaped for engagement lateral to the bicycle is considered. It enables the secure transmittal of force throughout the full rotation of the crank as well as unimpeded disengagement in a direction normal to the plane of rotation. The practical problem having prevented implementation is matching the rotational orientation of the pedal tracks about the pedal axis with the shoe cleat. One solution places the pedal track below the spindle axis, which maintains a given rotational orientation by virtue of gravity. This denies the use of a full length spindle and outboard bearing however and is mechanically unsatisfactory in regard to normal loading of the structure.
U.S. Pat. # 4,892,009, issued to the present inventor, describes a bicycle pedal which is intended to enable optimal efficiency in the transmission of torque from a cyclist's foot with complete safety that is mechanically reliable. The pedal disclosed therein describes two identical, opposed tracks, each comprised of bilaterally symmetric longitudinally contiguous surfaces with a lead having an ellipsoid shaped head with bilaterally adjacent fins tapering to an apex coincident the longitudinal axis of the pedal. The present invention represents an improvement of the pedal therein described.